GONADOTROPIN INHIBITORY HORMONE (GNIH) A LINK BETWEEN FEEDING AND REPRODUCTION IN THE CICLID FISH Cichlasoma dimerus.

TSUTSUI K; PEREZ SIRKIN, DI; SOMOZA GM; DELGADÍN TH; VISSIO, PG; SALLEMI JULIETA; DI YORIO, MP; TSUTSUI K; SOMOZA GM; PEREZ SIRKIN, DI; DELGADÍN TH; VISSIO, PG; SALLEMI JULIETA; DI YORIO, MP

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

GnIH downregulates reproductive function in vertebrates. Moreover,there are reports that propose that GnIH acts as an orexigenicpeptide in birds and mammals. Previously, we characterizedCichlasoma dimerus? GnRH variants (sGnRH, sbGnRH, cGnRH),the orexigenic peptide Neuropeptide Y (NPY) and GnIH peptide,and demonstrated that GnIH inhibited gonadotropin but stimulatedgrowth hormone release in adults of this specie. The general objective was to start studying GnIH as a link between feeding andreproduction in C. dimerus. We evaluate possible morphologicalrelationships between neurons and fibers of GnIH, GnRH variantsand NPY, and we analyze variations in the expression of thosepeptides in animals after fasting. By double label confocal immunofluorescences,we found that neurons of the nucleus olfacto retinalis(NOR) co-expressed GnIH and sGnRH, and that some fibersco-expressed both peptides while others were immunoreactive (-ir)to each one at hypothalamic level. There were no contacts betweensbGnRH or cGnRH fibers with GnIH neurons in the NOR. GnIH-irneurons of the hypothalamus did not co-express any GnRH variant.GnIH-ir fibers were observed in close proximity to NPY-ir fibers athypothalamic level and few contacts between cGnRH-ir and GnIH-irfibers were observed in midbrain. On the other hand, animals wereisolated in aquaria and daily fed at a fix time. After an adaptationperiod, they were randomly assigned to feeding or fasting groups.Four weeks later, variations in mRNA levels of those peptides weredetermined by real time PCR in telencephalon, hypothalamus andmedium-posterior brain. Fasting conditions induced a significantdecrease in GnIH mRNA levels (p=0.0375) in the hypothalamus, aclear tendency of decreasing in NPY expression but no changes forGnRH variants in telencephalon and medium-posterior brain. Takinginto account our results, we proposed that GnIH could act as a linkbetween feeding status and reproduction in C. dimerus.